The Yale Map Collection has the largest collection of maps in Connecticut and one of the largest university collections in the United States. Its collections are geographically comprehensive and consist of over 200,000 map sheets, 3,000 atlases, and 900 reference books.

The Map Collection holds approximately 11,000 rare map prints and manuscripts. These are generally identified as pre-1850 maps and can manifest themselves as large and small flat sheet maps, covers, globes, globe gores, wall maps, as well as copper and wood block engraved plates. These rare maps cover the world in scope. Most are single sheet maps, but there are some series maps as well. The majority of the rare Collection focuses on North America and includes many maps associated with American history. Patrons can view maps owned by prominent American figures such as George Washington and Benjamin Franklin, early world maps showing geographic perceptions of the period such as Johann Ruysch's 1507 map of the world (Universalior cogniti orbis tabula ex recentibus confecta observationibus), claimed possessions of North America such John Mitchell's Map of the British and French dominions in North America, significant historical boundaries such as the Charles Mason's Map of the Mason-Dixon line between Maryland and Pennsylvania (1768), and the beginnings of American cities such as the 1721 French manuscript map of New Orleans (Plan de la Nouvelle Orleans).

Other prominent rare maps available for patrons to access include maps by famous cartographers such as Joan Blaeu, Vincenzo Coronelli, and Jodocus & Henricus Hondius. Of the rarest maps in the Collection that stand out, the Bernardus Sylvanus Maps (1511)based on Ptolemy's work and printed in both black and red ink, along with prints of Vincenzo Coronelli's globes and gores and Giacomo Maggiolo's manuscript Portolan Chart (1553) are good examples.

In areas of historic cartography where the Collection is lacking, it is supplemented by many many facsimiles. There are many single sheet facsimile reproductions filed in with the original rare maps as well as several facsimile atlases in the Lanman Reading Room. High quality facsimiles of famous maps and atlases such as the 1513 Piri Reis map and Miller Atlas can be viewed in the Collection.

Other reproductions covering many important atlases of the 15th , 16th , and 17th century include Bleau's The Light of Navigation (1612), De Jode's Speculum Orbis Terrarum (1578), Waghenaer's Mariners Mirrour (1588), Abraham Ortelius's Theatrum Orbis Terrarum (1570), Claudius Ptolemy's Cosmographia (1482), and Mercator-Hondius-Janssonius' Atlas (1636). Many of these facsimile atlases can be view in the Lanman Reading Room.

The policy on viewing rare maps in the Collection limits patrons to viewing only one rare cartographic item at a time. There are exceptions for viewing more than one rare map at a time such as viewing for comparison, but it must first be cleared with the Maps Curator. See the following link for more information on rare map viewing policies. It is best to set up an appointment with the Map Collection staff if patrons wish to view rare maps. See the following link for more information on services.

There is a recent cataloging and digitizing project underway in the Map Collection to get all of the Collections rare maps fully cataloged, digitized, and made available on the Library's Online Public Access Catalog, Orbis. The digital images of the maps are saved in the .jp2 format and can be access through a link in the Orbis record with a free browser plug-in that allows patrons to view the format. Currently, there are over 100 maps that have been fully cataloged and digitized, consisting mostly world and North American maps.